Fix: Replace GitHub checkout with Gitea checkout + Version bump

Checkout Action Migration:
- Replace all 'actions/checkout@v4' with 'https://gitea.com/actions/checkout'
- Fixes 'Bad credentials' errors when workflows try to access GitHub API
- Native Gitea checkout action eliminates authentication issues
- Applied across all 4 workflow files (CI, Security, Release, Docs)

 Version Increment: 3.1.1  3.1.2
- Core application version updates
- Web API version synchronization
- Documentation version alignment
- Badge and release example updates

 Problem Solved:
- Workflows no longer attempt GitHub API calls
- Gitea-native checkout action handles repository access properly
- Eliminates 'Retrieving the default branch name' failures
- Cleaner workflow execution without authentication errors

 Files Updated:
- 4 workflow files: checkout action replacement
- 13 files: version number updates
- Consistent v3.1.2 across all components

 Benefits:
- Workflows will now run successfully in Gitea
- No more GitHub API authentication failures
- Native Gitea action compatibility
- Ready for successful CI/CD pipeline execution

src/__init__.py

@@ -6,7 +6,7 @@ A comprehensive real-time water level monitoring system for the Ping River Basin
 in Northern Thailand, covering Royal Irrigation Department (RID) stations.
 """
 
-__version__ = "3.1.1"
+__version__ = "3.1.2"
 __author__ = "Ping River Monitor Team"
 __description__ = "Northern Thailand Ping River Monitoring System"
 

src/main.py

@@ -297,7 +297,7 @@ Examples:
     )
     
     logger.info("🏔️ Northern Thailand Ping River Monitor starting...")
-    logger.info(f"Version: 3.1.1")
+    logger.info(f"Version: 3.1.2")
     logger.info(f"Log level: {args.log_level}")
     
     try:

src/web_api.py

@@ -143,7 +143,7 @@ async def lifespan(app: FastAPI):
 app = FastAPI(
     title="Northern Thailand Ping River Monitor API",
     description="Real-time water level monitoring system for Northern Thailand's Ping River Basin stations",
-    version="3.1.1",
+    version="3.1.2",
     lifespan=lifespan
 )